Submission #1279603

#	Time	Username	Problem	Language	Result	Execution time	Memory
1279603		hiepsimauhong	Railway (BOI17_railway)	C++20	100 / 100	89 ms	33964 KiB

railway

#include <bits/stdc++.h>

using namespace std;

using ll = long long;
const int64_t oo = 1e9;
#define int long long
#define float long double

#define quickly ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define FOR(I, L, R) for(int I(L) ; I <= (int)R ; ++I)
#define FOD(I, R, L) for(int I(R) ; I >= (int)L ; --I)
#define FOA(I, A) for(auto I : A)
#define print(A,L,R) FOR(OK, L, R){if(A[OK]<=-oo||A[OK]>=oo)cout<<"- ";else cout<<A[OK]<<' ';}cout<<'\n';
#define prints(A) FOA(OK, A){cout<<OK<<' ';}cout << '\n';
#define printz(A,L,R) FOR(OK, 0, L){FOR(KO, 0, R){if(A[OK][KO]>-oo&&A[OK][KO]<oo)cout<<A[OK][KO]<<' ';else cout << "- ";} cout << '\n';}cout << '\n';
#define fs first
#define sd second
#define th second.second
#define ii pair<int,int>
#define iii pair<int, ii>
#define all(A) A.begin(), A.end()

const int N = 1e5 + 5;
const int mod = 1e9 + 7;

int n, m, k, el;
int up[N][20], h[N], st[N];
int lazy[N], edge[N];
vector<ii> g[N];

void DFS(int u, int par){
        st[u] = ++el;

        FOA(e, g[u]){
                int v = e.fs, w = e.sd;
                if(v == par){
                        continue;
                }
                edge[v] = w;

                h[v] = h[u] + 1;
                up[v][0] = u;
                FOR(i, 1, 17){
                        up[v][i] = up[up[v][i - 1]][i - 1];
                }

                DFS(v, u);
        }
}

int LCA(int u, int v){
        if(h[u] > h[v]) swap(u, v);

        int c = h[v] - h[u];

        FOR(i, 0, 17){
                if(c >> i & 1){
                        v = up[v][i];
                }
        }

        if(u == v) return u;

        FOD(i, 17, 0){
                if(up[v][i] == up[u][i]){
                        continue;
                }
                v = up[v][i];
                u = up[u][i];
        }
        return up[v][0];
}

void add(int u, int v){
        lazy[u]++; lazy[v]++;
        lazy[LCA(u, v)] -= 2;
}

void DFS_DP(int u, int par){
        FOA(e, g[u]){
                int v = e.fs;
                if(v == par){
                        continue;
                }
                DFS_DP(v, u);
                lazy[u] += lazy[v];
        }
}

signed main(){ quickly
        cin >> n >> m >> k;

        FOR(i, 1, n - 1){
                int u, v;
                cin >> u >> v;
                g[u].push_back({v, i});
                g[v].push_back({u, i});
        }
        DFS(1, -1);

        while(m--){
                int s; cin >> s;

                vector<int> pos;
                FOR(i, 1, s){
                        int v; cin >> v;
                        pos.push_back(v);
                }

                sort(all(pos), [&](int &u, int &v){
                        return st[u] < st[v];
                });
                pos.push_back(pos[0]);

                FOR(i, 0, s - 1){
                        add(pos[i], pos[i + 1]);
                }
        }

        DFS_DP(1, -1);

        vector<int> ans;
        FOR(i, 2, n){
                if(lazy[i] >= 2 * k){
                        ans.push_back(edge[i]);
                }
        }
        sort(all(ans));

        cout << ans.size() << '\n';
        prints(ans);
}

• Subtask 1: 8 / 8
• Subtask 2: 15 / 15
• Subtask 3: 7 / 7
• Subtask 4: 29 / 29
• Subtask 5: 16 / 16
• Subtask 6: 25 / 25